Agricultural Chemistry

a science concerned with means of affecting chemical and biochemical processes in the soil and plants, with the mineral nutrition of plants and with the use of fertilizers and other chemical means to improve soil and increase yield. Agricultural chemistry also deals with several other means of increasing yield, such as herbicides and growth stimulants, and serves as the scientific basis for introducing chemical processes into agriculture. In its aims, methods, and subject areas of research, agricultural chemistry is related to both the chemical and the biological sciences. It is also closely related to soil science, farming, meteorology, plant physiology and biochemistry, agricultural microbiology, physics, and chemistry. Its primary subdivisions are plant nutrition, the interaction of soils and fertilizers, evaluation of particular types and kinds of fertilizers and the methods of applying them, soil improvement by chemical means—for example, the application of lime or gypsum—and research into and use of chemicals for weed control.

The first book on the fundamentals of agricultural chemistry was published in 1761 by I. Valerius, a Swedish chemist. In the 1830’s a French scientist, J. Boussingault, began to study the circulation of chemical substances in agriculture. In 1840, J. Liebig, a German scientist, showed in his book Chemistry as Applied to Agriculture and Physiology that plants are nourished not by humus or mulch, as many scientists had thought, but by mineral salts. Liebig proposed to convert bone meal into superphosphate, but it was J. Lawes, founder of the Rothamsted Experimental Station in England in 1843, who built the first superphosphate factory in the world. The Rothamsted Station is still one of the most important centers for research in agricultural chemistry in England today.

Research in agricultural chemistry at experimental stations began to develop in Germany in the 1860’s. In 1859, J. Sachs and J. A. L. W. Knop, German scientists, introduced a nutrient mixture for raising plants under artificial conditions. In 1886, German agrochemist H. Hellriegel first demonstrated the nitrogen-fixing role of rhizobium bacteria in the process by which leguminous plants obtain nitrogen from the atmosphere. In the United States research in agricultural chemistry developed after the establishment in 1887 of a network of experimental stations and agricultural colleges under existing universities. The work of E. Hilgard and S. Hopkins in the United States provided valuable materials for studying the soil chemistry and fertilization systems under crop rotation. There are government-run agricultural chemistry institutes as well as institutes run by the major fertilizer-producing companies in capitalist countries having advanced chemical industries. The translated works of such contemporary scientists as E. Russell in England, L. A. Desmoulins in France, E. Mitscherlich in the German Democratic Republic, and F. Bear in the United States are well known in the USSR.

In Russia, M. V. Lomonosov gave the earliest scientific commentary on agricultural chemistry. He was the first to explain that humus soil is derived from organic plant fragments. In 1825, M. G. Pavlov, a professor at Moscow University, published the first Russian manual on the subject, entitled Agricultural Chemistry. In the 1860’s, A. N. Engel’gardt organized a laboratory for agricultural chemistry at the St. Petersburg Agricultural Institute and proposed the use of phosphorites as fertilizer. The activity of D. I. Mendeleev in the field of agricultural chemistry also dates from this period; experiments with mineral fertilizers in different geographical regions were initiated under his direction.

The scientific and public activity of K. A. Timiriazev had great importance in developing agricultural chemistry in Russia. He initiated the first ereenhouse experiments conducted on plant nutrition. Insufficient attention was paid to agricultural chemistry in prerevolutionary Russia; the higher agricultural institutes did not have separate sub-departments in this area. The two chief centers for research in agricultural chemistry were the subdepartment of private crop production at the Moscow Agricultural Institute (now the K. A. Timiriazev Moscow Agricultural Academy), headed by D. N. Prianishnikov, and the subdepartment of soil science at the Forestry Institute in St. Petersburg, headed by P. S. Kossovich. Great credit is due Prianishnikov for working out some of the most important theoretical and practical problems in this field. He published extensively on plant nutrition, effects of fertilizers and their practical application, and other important questions. The publications of K. K. Gedroits on the absorptive capacity of soils and those of A. G. Doiarenko, who worked out a series of precise methods for determining the dynamics of soil processes in relation to changes in its air and water regimen, are also important.

After the Great October Socialist Revolution major scientific-research centers and experimental stations were set up; specialized subdepartments of agricultural chemistry were introduced in the agricultural institutes in 1928. In 1919, on the initiative of D. N. Prianishnikov, E. V. Britske, and la. V. Samoilov, the Scientific Fertilizer Institute was established; in 1933 it was renamed the la. V. Samoilov Scientific Research Institute for Fertilizers, Insecticides, and Fungicides. In 1923 this institute organized the Dolgoprudnyi Experimental Field (now the D. N. Prianishnikov Experimental Station for Agricultural Chemistry at Dolgoprudnyi), where field tests have been conducted for many years on mineral fertilizers and on soil treatment with lime and phosphorites, where various types of fertilizers and herbicides are studied, and where theoretical questions are worked out under field conditions. The All-Union Institute of Fertilizers and Soil Science was created in 1931, and in 1944 a laboratory for agricultural chemistry was organized at the V. V. Dokuchaev Soil Institute.

Under Soviet power scientists have carried out a whole range of research programs to increase soil fertility and crop yield. Among the Soviet researchers who have played important roles in advancing knowledge of soil characteristics to improve plant nutrition and the application of fertilizers are N. S. Avdonin, D. L. Askinazi, E. V. Bobko, M. V. Katalymov, A. T. Kirsanov, V. M. Klechkovskii, A. N. Lebediantsev, P. G. Naidin, Ya. V. Peive, A. V. Peter-burgskii, I. I. Siniagin, F. V. Turchin, and F. V. Chirikov. Much work has been done in researching the effectiveness and use of various types of fertilizers and in applying trace elements to various kinds of crops. Soviet agricultural chemists have shown that applying superphosphate in granulated form affects its interaction with the soil, microflora, and plants; its absorption into the soil sharply decreases while its utilization by the plants increases. Much attention is paid to questions of local conditions—that is, whether seed holes, seed hills, or furrows were used—in applying fertilizer. The creation of special institutes and experimental stations in the USSR to study cotton, sugar beets, flax, potatoes, tea, and other crops has led to a great number of experiments on the effects of fertilizers on the quantity and quality of the crop yields. In 1963–65 an ag-rochemical soil map of the USSR was drawn up at the V. V. Dokuchaev Soil Institute. Seven soil zones were laid out, and within each zone regions were distinguished by the degree to which mineral fertilizers are effective. In 1964 an agrochemical service, with a network of laboratories, was organized in the USSR to introduce chemical processes into agriculture.

Agricultural chemistry today must carry out further practical and theoretical work in root nutrition in order to raise the coefficient of fertilizer consumption, develop methods to increase plant utilization of the soil’s nutrient elements, and develop new and better fertilizers. Scientific research in agricultural chemistry is being conducted at the central research institutes, at numerous zonal institutes and experimental stations, and in agricultural institutes and university biological and soil subdepartments, where personnel for this field are trained.

Both chemical and biological methods are used in research on agricultural chemistry. Chemical methods, used in laboratories, are based on the analysis of plant, soil and fertilizer samples. Biological methods include tests in greenhouses, experimental fields, and in agricultural production itself. Biological experiments are valuable because they definitively answer questions of crop response to specific fertilizers. Some experiments are performed in special greenhouse containers. Certain theoretical questions can be studied by this method—plant nourishment, the relation of the conditions of nourishment to the plant cycle, and the effect that conditions of nourishment have, at different periods of a plant’s growth, on its chemical composition and on the quality of the crop yield. The development of the water-culture method has made hydroponics—the artificial production of vegetables by growing them without soil—possible.

Field experiments are conducted by fertilizing different plots of ground while varying the types and amounts of fertilizer or the techniques of application. These experiments, used for scientific research, serve as a basis for determining the proper utilization of fertilizers in agriculture.

Experiments in agricultural production differ from those in experimental fields in scale; the effect of fertilizers is tested in large fields with the agricultural technology and machinery used at a given farm. This makes it possible to ascertain not only whether crop yield has increased but also whether the recommended methods for applying the fertilizer are economically feasible.

The latest findings in chemistry and physics are applied to research in agricultural chemistry. A major role is played by the tracer technique, which makes possible a more precise determination of what elements have been assimilated into the soil, how they were absorbed by the plants, and so on.

Agricultural chemistry has enormous importance for the national economy. The scientifically based recommendations offered by this science for practical use make it possible to improve soil fertility and increase crop yields. Mineral fertilizer industry and agronomic ore-processing industry—dealing with phosphate rock, potassium ore, and boracic ores—have arisen as a result of the gains made in this field in the USSR and abroad. Many Soviet agricultural chemists are members of the International Association of Soil Scientists, of the All-Union Society of Soil Scientists, and of the D. I. Mendeleev All-Union Chemical Society. Results in this field are published in the journals Agrokhimiia (Agricultural Chemistry), Khimiia v sel’skom khoziaistve (Chemistry in Agriculture, since 1963), Pochvovedenie (Soil Science) and in a series of regional monographs, Agrokhimicheskaia kharakteristika pochv SSSR (Agricultural Chemical Characteristics of the Soils of theUSSR), published by the V. V. Dokuchaev Soil Institute. Manuals on fertilizer use and on introduction of chemical processes into agriculture are also published. Journals in this field are published in many countries and an international journal, Agrochimica, has been published in Pisa since 1957.